1. Field of the Invention
This invention relates in general to an assembly structure. More specifically, the present invention relates to an assembly structure of an optical film and a frame.
2. Description of Related Art
As the multimedia technology is highly developed, transmission of image information is currently changed from analog to digital. To comply with the modern life style, lighter, thinner and smaller video or image devices are highly desirable. Although the traditional cathode ray tube (CRT) display has superior display quality and low cost, the CRT display fails to meet the present market demand, namely, lighter, thinner, smaller and low power consumption requirements due to its funnel structure. Furthermore, the radiation issue of the CRT display is also a serious problem for the viewer's eyes. In recent years, since the optoelectronic technology and the semiconductor device technology become more mature, the flat panel displays are accordingly developed. Among the flat panel displays, the liquid crystal display (LCD) is widely applied to gradually replace the traditional CRT display, and has become a main stream of display on the market due to its advantages of low operation voltage, radiation free, light, thin and small volume.
The LCD mainly comprises a liquid crystal panel and a backlight module (B/L). The liquid crystal itself injected into the liquid crystal panel cannot illuminate. Therefore, the liquid crystal panel has to be illuminated by a plane light source provided by the backlight module, so that the LCD can display images. The conventional backlight module comprises a line light source, a light guide plate (LGP) and a frame. The line light source is usually arranged at one side of the light guide plate, and the light guide plate can convert the line light source into a plane light source. In addition, the frame is used to receive the light guide plate and the line light source so that the light guide plate and the line light source can be integrated. In order to increase the brightness of the backlight module and the display ability of the liquid crystal display, one or more optical films can be arranged above the light guide plate.
FIG. 1A is a schematic diagram of a conventional LCD before an optical film and a frame are assembled. FIG. 1B is a schematic diagram after the optical film and the frame in FIG. 1A are assembled. Referring to FIGS. 1A and 1B, the conventional optical film 110 has many positioning members 112 (only one is depicted) each extending and protruding from the edge of the optical film 110. The frame 120 is arranged in a manner to surround the optical film 110. A number of longitudinal slots 122 are formed on the frame 120 at locations corresponding to the positions of the positioning members 112 of the optical film 110. When assembling the optical film 110, the positioning members 112 are set to correspond the longitudinal slots 122 so as to position based on the fit between the positioning members 112 and the positioning members 112.
However, the aforementioned conventional method for fixing the optical film onto the frame has following drawbacks. The longitudinal slots on the frame have no restriction mechanism. The positioning members of the optical film are merely inserted into the longitudinal slots. Accordingly, positioning errors and shifts of the optical film might easily occur. In addition, when the backlight module needs to be turned over during the assembly of the liquid crystal display, the positioning members of the optical film might get separated from the longitudinal slots 122, causing the optical film slide or shift.
Furthermore, in the conventional technique, a fixing tape 130 is further adhered on the optical film 110 and the frame 120 to increase an fixing strength between the optical film 110 and the frame 120. FIG. 2 is a schematic diagram showing that a fixing tape has been adhered onto the optical film and the frame in FIG. 1B. Referring to FIG. 2, the fixing tape 130 is arranged above the positioning member 112 of the optical film 110 and the longitudinal slot 122 of the frame 120. To adhere the fixing tape 130, the frame 120 located at the two sides of the longitudinal slot 122 can be glued, or the positioning member 112 the frame 120 located at the two sides of the longitudinal slot 122 can be globally glued.
However, using the fixing tape to increase the positioning effect still has the following problems. If the optical film and the frame are globally glued, the optical film might be affected by temperature or humidity so as to cause a waving phenomenon. Therefore, the quality of the outgoing light of the backlight module is adversely affected. In addition, if only the frame is glued, the fixing tape will not create a fixing effect to the positioning members. Therefore, the positioning members will still separate from the longitudinal slots, so that the optical film will slide off. Moreover, although the additional fixing tape can increase the fixing effect, a step of adhering the fixing tape is further required during the assembly, so that the assembling time increases and the material cost for the assembly also increases.